Facts About Coal and Minerals Contents

FACTS ABOUT COAL AND MINERALS CONTENTS

Facts About Coal and Minerals I. Overview...... 3 2. Mining and the Economy...... 4 3. Resources ...... 6 What are coal and minerals?...... 6 What are reserves and resources?...... 7 Selected tables and trivia...... 8 4. Production and Preparation ...... 11 The process of mining...... 11 Major mined products from your state...... 13 Mining methods...... 15 Preparation...... 16 5. Coal and Mineral Use...... 17 6. Mining’s Workforce ...... 21 7. Mining and the Environment...... 23 8. Transportation...... 27 9. Exports and Trade...... 30 10. Glossary...... 33

1 Haul trucks used in surface mining can hold more than 400 tons of ore.

2 OVERVIEW | How has mining touched your life today?

Think of your everyday life…. Do you drive or bike to work or school? The iron ore, bauxite, copper, platinum and other minerals used in the manufacture of cars and bicycles are products of mining. Do you use a computer? Did you know it takes as many as 66 minerals to make the screen, case, chips, circuitry and battery? And it is likely that nearly half the electricity you used today was generated by coal and uranium, both products of mining.

We are surrounded by these raw materials — minerals and coal — that make nearly everything possible in our daily lives. But we often take them for granted because Did they are everywhere in our lives, even when we don’t see you them. They keep our lights on, provide essential building blocks for manufacturing and provide materials vital to know? advanced technologies we all depend on.

The average person in the U.S. For the U.S., mining has a direct economic impact of uses about 40,000 pounds of about $700 billion annually, or about three percent of the newly mined minerals – including U.S. gross domestic product (GDP), which is a measure of the market value of goods, services and structures three tons of coal – each year. produced in a country during a given time period. Mining activity takes place in all 50 states; in fact the U.S. has significant deposits of 78 minerals and major commodities - the most of any nation.

Today’s mining industry that produces these building blocks of American prosperity utilizes sophisticated equipment and a highly skilled and trained workforce to not only mine, but also to restore land after resource extraction has occurred.

All aspects of our economy including electricity, communications, transportation systems, computer networks, national security, space and medical technology require minerals and coal. Fortunately, the U.S. is home to extensive domestic reserves of many important mineral resources and the world’s largest supply of recoverable coal.

Although the U.S. has an abundance of high quality, diverse mineral resources, due to the lengthy federal permitting process, it can take seven to 10 years for a mine to receive approval to operate.

3 MINING and the ECONOMY

The products of mining take center stage in helping fulfill our advanced society’s most basic needs. An abundant food supply, clothing, shelter, electricity, transportation and communication would not be possible without mining. The typical house contains concrete and masonry block in the foundation, gypsum wallboard and copper pipes and wiring — to name just a few mined products. Coal provides a third of the electricity we rely on — and it takes at least 29 different minerals needed to get that electricity to our homes and businesses. Nuclear energy, which is generated from uranium, provides 19 percent of our electricity.

According to the U.S. Geological Survey (USGS), $109 billion of coal and minerals were mined in 2018, with $82 billion of non-fuel minerals processed into $766 billion worth of products.

USGS and the U.S. Department of Commerce esti- mate that industries, such as construction and durable goods manufacturing, that use processed mineral material added $3.0 trillion to the U.S. economy in 2018 — or about 15 percent of GDP. A wind turbine may contain 335 tons of steel, 4.7 tons of copper, 13 tons of fiberglass, 3 tons of alumi- Aside from their dollar impact, these minerals have num and 1,200 tons of reinforced concrete. other tangible benefits. The National Research Council of the National Academy of Sciences concluded that one of the primary advantages the U.S. has over its strongest industrial competitors is its domestic resource base. For example, with affordable and abundant domestic coal, U.S. electricity costs are highly competitive, an asset in the global marketplace.

Mining companies also pay taxes to the communities in which they operate. Companies pay more than $40 billion in federal, state and local taxes on company profits and employee wages, property taxes on equipment and structures, and excise taxes According to the National Park Service, the Statue of Liberty contains 31 tons of copper on output. 3/32 inches thick.

4 MINING and the ECONOMY

Direct & Indirect Contribution Labor Income Employment to GDP Number (Millions) (Millions) Alabama 33,300 $1,903 $4,287 Alaska 10,122 604 1,908 Arizona 62,189 3,827 15,405 Arkansas 13,024 622 1,029 California 89,630 6,742 14,043 Colorado 42,202 2,656 7,129 Connecticut 8,108 573 1,048 Delaware 1,884 123 250 D.C. 2,265 250 444 Florida 59,884 3,306 5,343 Georgia 38,094 2,204 4,537 Hawaii 3,431 180 352 Idaho 16,494 774 2,049 Illinois 54,764 3,716 8,380 Indiana 36,021 2,136 5,227 Iowa 12,398 644 1,462 Kansas 9,911 448 1,846 Kentucky 48,221 2,783 5,099 Louisiana 23,034 1,377 2,744 Maine 4,815 201 326 Maryland 26,710 1,793 2,105 Massachusetts 14,160 1,092 2,220 Michigan 36,491 2,072 5,405 Minnesota 53,271 3,322 7,524 Mississippi 10,078 509 882 Missouri 30,942 1,847 2,801 Montana 18,977 1,065 2,491 Nebraska 7,382 393 771 Nevada 55,056 3,831 13,226 New Hampshire 5,469 313 535 New Jersey 20,232 1,869 2,340 New Mexico 18,559 1,076 2,415 New York 45,640 3,289 7,087 North Carolina 27,663 1,451 3,545 North Dakota 7,963 556 1,306 Ohio 51,388 3,023 6,524 Oklahoma 17,053 879 2,292 Oregon 16,615 912 2,332 Pennsylvania 108,256 6,615 10,913 Rhode Island 2,408 152 274 South Carolina 22,100 1,150 1,773 South Dakota 5,472 283 556 Tennessee 24,316 1,390 2,380 Texas 100,662 6,103 18,078 Utah 43,517 2,412 4,899 Vermont 3,758 165 335 Virginia 48,803 3,426 6,429 Washington 19,305 1,243 4,355 West Virginia 55,418 3,657 7,347 Wisconsin 21,992 1,121 3,822 Wyoming 41,879 2,981 7,624 Total Operations 1,531,327 95,057 $217,493

Sources: NMA analysis based on Mine Safety & Health Administration (2017) data and IMPLAN modeling system

5 RESOURCES | What are coal and minerals?

Coal, copper, gold, gravel and iron ore are all mined, but are they all minerals?

Not all of them. Scientifically, a mineral is Is coal being formed today? a naturally formed inorganic solid (element or It’s likely that the process that formed coal and chemical compound) with a limited range of other fossil fuels is still occurring in swampy chemical composition and an orderly internal areas where plant material accumulates. atomic structure. Coal and aggregates such as sand and gravel contain varying amounts of mineral matter, but are technically rocks.

Coal is a carbonaceous sedimentary rock. It is formed from organic matter and contains carbon and other elements, such as hydrogen, oxygen and nitrogen. Most coal was formed 280 to 345 million years ago as trees, ferns and other plants decomposed and were buried under prehistoric seas and swamps. Pressure and temperature compressed and altered the plant remains, concentrating carbon content, and over millions of Minerals, also called nonfuel or hardrock min- years, transformed the material into coal. erals, are classified as metallic and nonmetallic:

Coal is divided into four major types based on the Metalllic minerals are further classified as amount of transformation undergone from the ferrous and nonferrous. The category of earlier plant and peat stages, heating value and ferrous minerals includes iron and iron alloys other characteristics: such as steel. Nonfer- Lignite is a coal with generally high moisture and rous minerals include, ash content and low carbon content. Significant among many others, reserves are located in Texas, North Dakota and copper, silver, platinum, Montana. gold, uranium and zinc.

Subbituminous coal has a higher heating value Nonmetallic minerals in- than lignite. Wyoming produces the bulk of sub- clude “structural ma- bituminous coal in the Powder River Basin area. terials” — stone, sand, gravel and synthetic ma- Gold Ore Bituminous coal is a soft, intermediate grade that terials like cement. They usually are composed of is most common in the United States. It is mined some of the 25 most abundant minerals and are chiefly in Appalachia and the Midwest. used for the nation’s infrastructure.

Anthracite is the hardest type of coal, consisting Nonmetallic minerals also include “industrial of nearly pure carbon. Mined in Pennsylvania, it minerals,” which are used as paper coatings, has the highest heating value and lowest mois- paints, varnishes, enamels, fertilizers, abrasives, ture and ash content. and so forth. These minerals include sulfur, salts, limestone, clays, barite and industrial diamonds. 6 RESOURCES | What are reserves and resources?

A mineral deposit is a naturally occurring mineral accumulation that may have potential value. An ore deposit is a mineral ORE is rock deposit that has been tested and is known to be of sufficient that contains quality to be mined economically. Sometimes several metals occur in the same deposit, such as lead, zinc and copper, or important minerals, silver and gold. including metals.

Resources are concentrations of minerals, coal or other commodities in such form that they can be extracted with current technology or the extraction potential is considered feasible in the future. Resources may be known to exist, or they may be surmised to exist based on geologic evidence. U.S. coal resources are estimated to be nearly 4 trillion tons, enough to provide fuel for many generations of Americans.

Reserves are known, identified resources from which a usable mineral commodity can be technologically, economically and legally extracted at the time of determination. A fall in price, for instance, can change the character of a deposit from “reserve” to “resource.” Additionally, exploration drilling that further delineates a deposit can add to reserves. According to the U.S. Energy Information Adminis- tration (EIA), the U.S. has more than 250 billion tons of recoverable coal reserves — enough to last more than 300 years at current rates of use.

Where are resources found? Most U.S. mineral resources are located in the Western states including Alaska, and the areas with the most promise for ore discoveries are primarily within federally-managed public lands. The Bureau of Land Management (BLM) manages 700 million acres of subsurface public land, representing as much as 60 percent of the nation’s hardrock mineral land area; however, less than half of that area currently is open for mineral exploration and production. Mining Claims on Federal Land in the West

Coal is present in 38 states and underlies nearly half a million square miles, or 13 percent of the nation’s land area. Coal reserves are split between the Eastern and Western states — the most important coal deposits in the East are in Appalachia, which includes portions of nine states. The West contains the Wyodak coalbed, which is the nation’s leading source of coal and part of the Powder River Basin of Wyoming and Montana. In the interior states, coal occurs in several basins located from Michigan to Texas.

BLM U.S. Forest Service Mining claim

www.geocommunicator.gov 7 RESOURCES | Where are coal and minerals found?

Major Metals Mineral Producing Areas

Gold Silver Copper Molybdenum Platinum Lead Zinc Iron Titanium Magnesium Beryllium Rare Earths U.S. Geological Survey, Minerals Commodity Summaries

Major Coal Reserves

Energy Information Administration (EIA)

8 RESOURCES | Tables and trivia

U.S. coal recoverable reserve base Aluminum was considered a rare metal and 2018, top 10 states a chemical curiosity until 1886. Researchers (billion short tons) in the U.S. and France independently discov- State Total Reserves ered the continuous electrolytic reduction 1 Montana 74.4 process used to make aluminum metal from 2 Illinois 35.7 bauxite. 3 Wyoming 35.3 4 West Virginia 16.4

5 Kentucky 13.9 6 Ohio 11.2 7 Pennsylvania 11.0 8 Colorado 9.5 9 Texas 9.0 10 New Mexico 6.7 Rest of U.S. 27.6

Total U.S. 252.7

Energy Information Administration

U.S. mineral reserves by commodity, 2018 uick % World q uestion Reserve Reserve In thousand metric tons of metal content: What are ‘precious’ metals? Barite 15,000 4.6 Copper 48,000 5.8 Precious metals are miner- Iron Ore 2,900,000 1.7 als that are relatively scarce Lead 5,000 60.0 and valuable, such as gold, Molybdenum 2.7 15.9 silver and platinum group Zinc 11,000 4.8 metals. In thousand metric tons of ore/rock: Phosphate Rock 1,000,000 1.4 In metric tons of metal content: Gold 3,000 5.6 Platinum Group Metals 900 1.3 Rare Earths 1,400,000 1.2 Silver 25,000 4.5 U.S. Geological Survey U.S. Mint American Eagle Bullion Coin

9 RESOURCES | How are coal and minerals found?

In order to maintain a national reserve base, geologists are continuously looking for new mineral deposits. The exploration process undertaken to find these elusive deposits can be compared to searching for a needle in a haystack.

GPS satellite Exploration often starts with literature and field investigation of a region covering up to 100,000 square miles. Bit by bit, the exploration team narrows this region down to smaller target areas that are considered highly favorable for mineral resource deposits. Tools such as remote sensing satellites help identify favorable areas in relatively inaccessible places. Global positioning systems (GPS) aid in pinpointing resource locations. Other tools of the modern explorationist include:

• Airborne magnetometers to detect minerals that affect the earth’s magnetic field;

• Geochemical prospecting using analyses of water, soil and vegetation to pinpoint How are minerals named? hidden concentrations of minor ele- For some common minerals, such as ments; and quartz and gypsum, the names are • Electrical, electromagnetic, seismic and ancient and the precise ori- radiometric techniques. gins are unknown. Newer minerals are named by the Once a promising site is identified, core mineralogist who first de- samples are taken and submitted to chemi- scribes them in print, and cal analysis, X-ray microanalysis and other are often named for a per- testing. If all of these tests indicate an eco- son or place. nomically viable deposit, a company can begin to decide if a mine should be constructed. Millions of dollars and upwards of five years are spent on a single exploration campaign that may or may not end in mineral production. U.S. Share of Worldwide Nonferrous Exploration Unlike most minerals, the location and quantity of U.S. Spending, 2019 coal reserves are fairly well known. As a result, coal ex- Paci c/SE Asia 4% ploration efforts are usually focused not on where coal deposits are, but rather on the geology and composi- U.S. tion of the reserves. The tools and techniques used to 10% gather and utilize these data range from the traditional to the cutting edge. As with minerals exploration, they Latin America include drilling for core samples to reveal cross sec- Rest of 28% tions of the underlying rock and coal strata, laboratory World 16% analyses, surveying and mapping — all of which help engineers plan the mine’s design and production plan. Australia Canada 14% 16% Africa 12%

S&P Global 10 PRODUCTION | The process of mining

While every mine has unique characteristics and some require special extraction techniques, The state with the most coal the essential process of mining — whether coal production is or hardrock — includes five basic phases: Wyoming which mined 304 million tons.,

Exploration — Today’s mining compa- Nevada is the state that pro- 1 nies use an array of techniques to pinpoint duces the most minerals overall, ore bodies and determine a site for a possible with production valued at $7.9 mine. Geologists map and take samples. They billion in 2018. are supported by geophysicists, drillers, environmental engineers, geochemical technicians, computer-aided design, information technology experts and office support. Environmental, engineering and cultural studies are also conducted. ously monitor mining progress. Environmental scientists and technicians make sure the envi- Permitting and Bonding — Before a ronment is protected. The logistics of running a 2 mining company can break ground, it must mining operation are supported by dozens of ad- go through permitting and bonding processes. ministrative personnel. Permits ensure that federal, state and local laws and regulations are followed (see p. 23 for a list). Processing — In both coal and miner- Financial bonds are secured to ensure that sur- 4 als mining, the extracted resource is often face-mined land will be returned to an agreed- sent from the mine to a processing facility. Rocks upon use at the completion of the mining pro- bearing mineral ores are crushed and subjected cess. to a variety of chemical reactions to remove the valuable metal from surrounding rock. Coal is Mining — Whether coal or hardrock, taken to preparation plants, where it is cleaned 3 mining operations themselves are usually one of two types — surface (also called “open pit”) or un- U.S. coal production by state, 2018 (million short tons) derground (also called “deep”). State Total % of Total U.S. Operations begin only after hun- 1 Wyoming 304.2 40.2% dreds of drill holes, metallurgical 2 West Virginia 95.4 12.6% tests and environmental studies 3 Pennsylvania 49.9 6.6% have confirmed that a new depos- 4 Illinois 49.6 6.6% it can be mined safely and profit- 5 Kentucky 39.6 5.2% ably and with minimal long-term 6 Montana 38.6 5.1% environmental impact. Mining en- 7 Indiana 34.6 4.6% gineers design mine plans and pro- 8 North Dakota 29.6 3.9% cessing plants. Drillers and blast- 9 Texas 24.8 3.3% ers shatter the ore-bearing rock so 10 Alabama 14.8 2.0% it can be removed with giant shov- Other States (13) 75.1 9.9% els and trucks. Mine geologists and Total U.S. 756.2 100% survey teams using GPS continu- Energy Information Administration, 2018

11 PRODUCTION and PREPARATION and separated by quality. Impurities in the coal are removed by various mechanical techniques, in- Estimated Nonfuel Minerals Values cluding pulsating water currents, rapidly spinning (billion dollars) water and liquids of different densities. In all cases, U.S. Materials Year metallurgists, mechanical engineers, electricians, Production Processed welders and other skilled technicians are critical to 2012 $76.5 $704 keeping the operation of these processing facilities 2013 $74.2 $665 running smoothly. (See page 16 for more informa- 2014 $77.6 $697 tion on processing). 2015 $78.3 $630 Restoration — Once mining is complete at 2016 $74.6 $675 5 a site, engineers, metallurgists and environ- 2017 $75.2 $727 mental specialists begin the restoration process 2018 $82.2 $766 — returning the landscape to its natural form or to USGS Minerals Commodity Summaries another acceptable use, such as recreation, wildlife habitat or economic development areas. At large coal surface mines and some minerals mines, reclamation often begins in the sections where the coal or minerals have already been removed, even while mining is continuing elsewhere at the site. Waste rock is treated and the topography is carefully con- toured. Mined areas can be successfully converted to wetlands and other approved uses. The earth is Since 1977, U.S. mining companies seeded with indigenous species, and biologists and have restored more than 3 million acres of mined land and have planted hydro-geologists monitor sites for years after min- more than 500 million trees. ing is completed to ensure environmental goals are met.

Mineral production is a cyclical business, with production levels for any given period showing peaks and valleys for almost every mineral. Production rates are determined by worldwide demand as much as by exploration success. Of 2,500 known minerals, about 50 are major economic commodities that are commonly explored, mined and traded internationally.

The United States produces 78 major mineral commodities, more than any other nation involved in mining. These include: antimony, bauxite, beryllium, borax, boron, clays, coal, copper, diamonds, diatomite, feldspar, gold, gypsum, iron ore, lead, limestone, molybdenum, perlite, phosphate rock, platinum and palladium, pumice, rare earth metals, salt, sand and gravel, silver, sodium sulfate, stone, trona and uranium. By comparison, Russia produces the next largest number of mineral commodities (60), followed by China (53), Canada (49), India (46), South Africa (44), Germany (44) and Australia (42).

12 PRODUCTION and PREPARATION Mined Products from Your State, 2018

Alabama Alaska Arizona Arkansas California Coal, cement, Coal, gold, lead, Coal, copper, Bromine, Boron, cement, stone, lime, silver, zinc, sand molybdenum, cement, sand gold, sand and sand and gravel, and gravel sand and and gravel, gravel, stone common clays gravel, stone, lime cement, stone, silver

Colorado Connecticut Delaware Florida Georgia Coal, gold, Common clays, Stone, sand Phosphate rock, Cement, Clays molybdenum, stone, sand and and gravel, stone, cement, (kaolin), stone, sand and gravel, gravel magnesium, sand and gravel, sand and gravel cement, stone gemstones zirconium

Hawaii Idaho Illinois Indiana Iowa Stone, sand and Lead, lime, Coal, sand Coal, cement, Cement, lime, gravel phosphate rock, and gravel, lime, sand and sand and gravel, sand and gravel, stone, gravel, stone stone, gypsum stone cement, tripoli

Kansas Kentucky Louisiana Maine Maryland Coal, helium, Coal, cement, Coal, common Sand and gravel, Coal, cement, cement, salt, sand and gravel, clays, salt, cement, stone peat, sand and stone, sand and stone, common sand and gravel, stone gravel clays gravel, stone

Massachusetts Michigan Minnesota Mississippi Missouri Common clays, Iron ore, Iron ore, sand Coal, clays Coal, cement, lime, stone, sand cement, nickel and gravel, (fuller’s earth, stone, lead, and gravel concentrates, stone, lime ball, bentonite) lime, sand and salt, stone, sand sand and gravel, gravel and gravel stone

USGS; state mineral offices; mining company websites 13 PRODUCTION and PREPARATION Mined Products from Your State, 2018

Montana Nebraska Nevada New New Jersey Coal, copper, Cement, sand Copper, gold, Hampshire Peat, sand palladium, ce- and gravel, lime, sand and Sand and and gravel, ment, platinum, stone, lime gravel, silver gravel, stone, greensand marl gold, sand and gemstones gravel

New Mexico New York North North Ohio Coal, copper, Cement, salt, Carolina Dakota Coal, cement, cement, potash, stone, sand and Clay, phosphate Coal, common lime, salt, sand sand and gravel, gravel, zinc rock, sand and clays, lime, and gravel, stone gravel, stone, sand and gravel, stone feldspar stone

Oklahoma Oregon Pennsylvania Rhode South Coal, cement, Cement, Coal, cement, Island Carolina iodine, sand diatomite, lime, sand and Sand and gravel, Cement, clay, and gravel, perlite, sand and gravel, stone stone gold, sand and stone gravel, stone gravel, stone

South Tennessee Texas Utah Vermont Dakota Coal, cement, Coal, cement, Coal, cement, Stone, sand Gold, cement, zinc, sand and salt, sand and copper, and gravel, talc, lime, sand and gravel, stone gravel, stone magnesium gemstones gravel, stone metal, salt, sand and gravel

Virginia Washington West Wisconsin Wyoming Coal, cement, Cement, Virginia Lime, sand and Coal, cement, lime, sand and diatomite, sand Coal, cement, gravel, stone bentonite clays, gravel, stone and gravel, zinc, lime, sand and helium, sand stone gravel, stone and gravel, soda ash, uranium

USGS; state mineral offices; mining company websites 14 PRODUCTION and PREPARATION | Mining methods

No matter what resource is being extracted, the process of modern mining is highly automated and technologically advanced. Today, sophisticated machinery is critical to mining.

For both coal and minerals, mining is usually accomplished by surface or underground mining techniques. The type of technique used depends on several factors, including resource type, location and the surrounding geology.

Other types of minerals mining include quarrying, a type of surface mining in which large blocks of rock are mined intact or the rock itself is the intended final product. Granite, limestone, marble and sandstone are often mined this way. Placer mining is used to recover precious materials, such as gold or platinum, from sand or gravel in streambeds. Sand Dragline controls at a Wyoming coal mine. and gravel are mixed with water and swirled or shaken so that the valuable heavy metals sink and the relatively lightweight sand stays on top to be washed away. Gold panning is a simple form of placer mining that is enjoyed by recre- ational miners.

Another method is the Frasch process, currently in use in sulfur mines in the Gulf of Mexico. In this process, hot water is injected into a native sulfur deposit that is melted underground and brought to the surface by compressed air.

Coal seams deeper than 200 feet below the surface are typically mined by underground methods. Deposits at a shallower depth are extracted by surface mining, which accounts for U.S. Coal Production, 63 percent of U.S. coal production.

2008-2018 Underground coal mining is usually one of four types: (million short tons) Total Coal Longwall – accounts for 55 percent of underground mine production. Year Production The longwall miner is a machine with a rotating drum that moves 2008 1,171.8 mechanically back and forth across a wide coal seam.

2009 1,074.9 Continuous – also known as room and pillar mining, this method 2010 1,084.4 accounts for most of the remaining underground production. Utilizing a 2011 1,095.6 special cutting machine, coal is removed from a seam and automatically 2012 1,016.5 transported by conveyor to the mine mouth. 2013 984.8 Conventional – one of the oldest, but increasingly less common, meth- 2014 1,000.0 ods of mining coal uses explosives to break up a coal bed. 2015 896.9 Shortwall – accounts for less than 1 percent of underground produc- 2016 728.4 tion. This method uses a continuous mining machine in a longwall-like 2017 774.6 method to mine smaller faces than are mined in longwall mining. 2018 756.2 EIA

15 PRODUCTION and PREPARATION | Preparation

The preparation process is crucial in readying Solvent extraction-electrowinning (SX-EW) is coal and minerals for the marketplace. This step a process that is used in copper production. The assures that the resource sent to the end user is process uses electricity to extract the metal from a solvent solution and attach it to a cathode. SX-EW of the highest possible quality. In the case of coal, has increased in use since the mid-1980s partly there is also an environmental benefit — physical because it can recover copper from lower grade coal cleaning can remove as much as 90 percent ores that otherwise could not be processed. of the inorganic, or “pyritic,” sulfur that could For both coal and minerals, the processing step is otherwise contribute to emissions during the referred to as beneficiation – the processing of coal combustion process. and ores to regulate size, remove impurities and Preparation plants crush and screen coal and improve quality. Some minerals undergo further employ a circuit of cleaning techniques to remove refinement, sometimes by a smelting process, to non-coal materials and separate the coal into dif- obtain the desired degree of purity. Once this level ferent quality grades. of purity has been achieved, the mineral is ready for commercial use, whether gold for electronics And for some minerals, including structural mate- and jewelry, copper for plumbing or electrical wire, rials like sand and gravel, washing and separating or one of many other potential end uses. for size is typically all that is involved.

For metallic ores, however, it is a different story. U.S. Per Capita Consumption of The number and complexity of steps in processing Minerals and Coal, 2018 these ores is often directly related to the complexity of the ore itself and the degree of purity needed Mineral Pounds for the end product. Cement 675 Clays 155 In order to separate the mineral from surrounding Coal 4,206 ore, the first step is typically to transport the ore to a mill, where the mineral is concentrated. The Copper 12 process begins by crushing or grinding the ore to Iron Ore 256 the degree of fineness needed to extract the min- Lead 12 eral material contained within. Then the mineral Phosphate Rock 182 is physically separated by leaching (using a perco- Salt 384 lating liquid to remove soluble parts), flotation or Sand and Gravel 7,345 solvent extraction. Stone 9,924 Flotation is a chemical and physical process in Zinc 6 which the ground ore is mixed with water and a Manganese 6 foaming agent. The slurry is then agitated, much Uranium (2014) 0.15 as if in a washing machine, and bubbles are cre- NMA calculations based on preliminary USGS, EIA and U.S. ated. The mineral material attaches to the bubbles Census Bureau data. and floats to the top to be skimmed off. This process makes it possible to access lower-grade mineral deposits that otherwise would not be utilized.

16 COAL and MINERAL USE From A-to-Z, U.S. Coal and Mineral Resources and Their Uses (abridged) Antimony Mica Batteries, cable sheaths, solder, fireworks, Electronic insulators, paints, joint cement, semiconductor technology, medicine. dusting agent. Beryllium Molybdenum Computers and telecommunications, aircraft Alloy and tool steels, cast irons, superalloys, alloys, fluorescent lamps, X-rays, nuclear industry. chemicals and lubricants. Coal Phosphate Rock The source of about 1/4th of U.S. electricity Fertilizers, livestock feed additives, elemental generation. phosphorus. Cobalt Perlite Superalloys for jet engines, chemicals, Roof insulation boards, filters, filter aids, permanent magnets, Tesla vehicles. horticulture. Copper Platinum Group Metals Electric cables and wires, switches, plumbing, Catalytic converters, jewelry, electrical heating, electric vehicle batteries, saucepans. contacts, dental alloys, pacemakers. Feldspar Silica Glass and ceramics, enamelware, soaps, bonding Computer chips, glass and refractory materials, agent. ceramics, abrasives. Gold Silver Dentistry, medicine, jewelry, coins, olympic Chemistry, jewelry, photography, silverware, medals, scientific, electronic instruments. currency, electronics, dental. Gypsum Sulfur Prefabricated wallboard, plaster, cement Sulfuric acid, fertilizers, chemicals, explosives, manufacture, agriculture. fungicides, dyestuff. Halite (salt) Titanium Food seasoning and preservation, soda ash, Jet engines, airframes, space and missile soaps, highway de-icing. applications. Iron Ore Uranium Steel manufacture, metallurgy by-products, Electricity generation, medicine, atomic dating. vehicle framing and parts, medicine, rail tracks. Lead Vanadium Batteries, solders, electrical and electronic Metal alloys, aerospace, dyes, target material applications. for X-rays. Lithium Zinc Electric vehicle and cellphone batteries, ceramics Protective coating for steel, die casting, and glass, medicine, lubricants and greases. component of brass, roof cladding.

17 COAL and MINERAL USE Communications Mining makes possible a wide range of necessary The revolution in consumer technologies products that sustain our way of life. The products for communications of mining are essential, not only to meet basic needs, and data have led to but also for higher aspirations — a continuously im- exciting new appli- proving standard of living, cleaner environment, and cations for minerals. Copper wiring, ceramic insulators, steel societal prosperity, security and stability. Here are printing presses, gold connectors and silicon chips just a few of the many ways coal and minerals benefit – all forms of communication, from newspapers to people every day. smart phones to satellites - require mineral components. A computer typically requires as many as 66 Agriculture minerals, including silicon, boron, lead, indium, stron- Minerals are needed tium, barium and phosphorous for the screen; calcium carbonate, talc, clays, sulfur and mica for the case; for our most basic silicon for the chips; gold, copper, aluminium, steel, requirement for life lithium, tungsten, chromium, titanium, silver, cobalt, — food. Although nickel, germanium, tin, lead, tantalum and zinc for the most people recog- circuitry; and cadmium and lithium for the battery. nize that magnesium, iron and zinc are im- Energy portant for healthy Coal accounts for about a quarter of the nation’s elec- diets, they don’t often connect minerals with productive tricity generation. Over the past four decades, as the farming. Fertilizers made from potash, phosphate rock U.S. economy has become increasingly dependent on and sulfur are essential to grow crops. Harvesting and electricity to meet energy demand. At the same time, transporting crops to market is achieved by machinery air quality has improved with declines in coal power and transportation vehicles made from minerals. Pro- plant emissions of sulfur dioxide, nitrogen oxide and cessing food takes still more machinery and equipment, particulate matter, according to U.S. Environmental as does packaging. Protection Agency (EPA) data. According to the Energy Information Administration Construction and Housing (EIA), coal-based power plants are expected to re- Minerals are society’s building blocks. Rocks and main a key source of electricity. Meanwhile, another minerals are present in nearly ev- product of mining, uranium, provides an additional ery building and structure — sky- 19 percent of electricity generation through nuclear scrapers, hospitals, bridges, power plants. Combined, coal and nuclear plants are factories, fast food restaurants responsible for nearly 50 percent of the nation’s elec- and the house in which you live. tricity. Minerals are commonly used in gypsum wallboard; aluminum or Liquid fuels also can be produced from coal. The pro- galvanized steel gutters; copper or duction of coal-to-liquid (CTL) transportation fuels stainless steel pipes; copper wiring; concrete begins with coal as a raw material or feedstock. The foundations; asphalt roof shingles; and windows made indirect liquefaction process is proven and already be- from glass (trona, silica, sand and feldspar). ing used in other parts of the world and can be an al- ternative to U.S. imported oil.

18 COAL and MINERAL USE

Medicine Modern medicine relies What are strategic minerals? on many drugs and tools made from minerals. Pro- Strategic minerals are those considered tection from X-rays is of- essential for a country’s economic and de- fered by a lead apron. Gold fense needs, such as metals for weapon is used in lasers, pacemak- systems, satellite communications, aircraft, ers and medical diagnostic automobile parts and medical instruments. tools. Sulfur and salts are basic ingredients in many drugs and preparations; and copper, zinc, iron, magnesium and many other minerals are used in vitamins, mineral supplements and medicines. Arts and Entertainment Much in the field of art and entertainment would be impossible without the products of mining. Consider a concert hall — the instruments and building itself are made of many minerals; the electricity for powering the event is likely to have F-22 Raptor, U.S. Air Force photo come from coal or uranium; and even the tickets for admittance to the event are likely to contain trona, limestone, gypsum, kaolin, sulfur, magnesium, sodium, What is coking coal? calcium and more. A bituminous coal, sometimes called met- Manufacturing and Consumer Goods allurgical coal, with special characteristics The products of mining have a huge impact in this that allows it to be converted into coke and area, from cell phones, appliances and cookware to used in the steel manufacturing process. cosmetics, toothpaste and fireworks. Virtually all consumer products contain natural resources from the earth, whether it’s soapstone for pow- U.S. Coal Supply End Uses, 2018 ders, trona for glass or gold for electronic connectors. It would 2% Steel 84% Domestic also be difficult, if not impossible, Production Power Generation to find an industry that does not use some form of rock or mineral 5% Industrial, Commercial, in manufacturing a product or Other providing a service. Even organic-based products frequently use 10% Exports rock or mineral-based materials. Kaolin clay, for instance, is used in coating paper, as well as in ceramics, paints, plastics, fiberglass, adhe- sives and rubber products. EIA 19 COAL and MINERAL USE | A closer look at coal

Coal is used in nearly every state, primarily to generate electricity. Today, many people don’t actually see coal the way they did 100 years ago, when it was widely used to heat homes. But coal is working just as hard for America as it did in the past — only in a different way.

Of the coal mined in the United States, more than 90 percent is used to generate electricity at home and abroad. Coal consumption for electricity has more than doubled from Power Sector Generation less than 400 million tons annually in the early 1970s to by Fuel, 2018 (billion kWh) about 800 million tons today. Coal is also used directly by industries and manufacturing plants, especially those making chemicals, cement, paper, ceramics and various metal products, to generate power and process steam. It is still an important source of coke for the steel industry, and coal coal byproducts serve as the basis for many day-to-day items, renewable / 28% including linoleum, synthetic rubber and insulation, and vari- other 11% ous compounds used in medications, detergents, perfumes and food preservatives. hydro 7%

At conventional power plants, pulverized coal is burned to nuclear natural gas produce high-pressure steam that drives an electric genera- 20% 34% tor. Some power plants are “mine mouth” facilities, constructed near one or more mines that provide a convenient source of coal. In general, each ton of coal used by a power plant generates about 2,000 kilowatt hours of electricity. A EIA pound of coal supplies enough electricity to light more than 100 9-watt (40-watt equivalent) compact fluorescent light bulbs for about an hour. Every American uses an average of 14 pounds of coal daily.

Aside from its abundance, coal’s low price in relation to competing energy sources is one of its major advantages as a fuel for electricity generation. EIA reports that coal averaged $2.06 per million Btu in 2018 — natural gas, on the other hand, averaged $3.55 per million Btu.

U.S. Electric Power Sector Net Generation, 1950-2018 (billion kWh) 5000 Renewable Hydro 4000 Nuclear

3000 Natural Gas 2000

1000 Coal

0 1950 1960 1970 1980 1990 2000 2018

20 EIA Monthly Energy Review Feb. 2020 MINING’S WORKFORCE

Annual Mining Wages vs. All Industries, 2018 All State Mining* Industries** 1 Alaska $112,717 $54,424 2 Nevada $98,289 $48,923 3 N.Dakota $94,728 $53,157 4 Hawaii $93,500 $48,377 5 Wyoming $92,765 $47,422 6 Montana $88,774 $42,315 7 Colorado $88,396 $59,305 8 West Va. $87,156 $45,780 9 Illinois $85,938 $60,424 10 Alabama $85,441 $46,510 All U.S. $78,920 $57,198 *Excludes oil and gas extraction. **Average. U.S. Bureau of Labor Statistics.

The mining workforce includes a broad range of This includes a level of sophistication that demands professions — from geologists and engineers to unprecedented skill, training and education. It is no surprise that as mining becomes increasingly accountants and equipment operators. In addition, high‑tech, computer programmers and technicians thousands of men and women who may never see are playing a greater role in mining’s future. a mine make their living building the equipment These advances have significantly altered the used to extract coal and minerals from the ground. overall size of the mining’s workforce. In recent Computerization, mechanization and technologi- years, the trend has been toward fewer, more cal innovations have had a tremendous effect on highly skilled mining personnel to operate sophis- American industry and mining in recent years. ticated equipment that performs tasks once done Although mining is still a demanding and often chal- by many laborers. lenging profession, today’s mining personnel are highly skilled and well-trained in the use of modern, state‑of‑the‑art instruments and equipment.

Mining Employment in the United States, 1990-2018 Sector 1990 1995 2000 2005 2015 2018 Metal 54,005 48,734 37,650 30,395 41,459 39,867 Non-metal 33,818 29,441 25,918 23,039 21,235 19,773 Coal 146,505 103,076 76,025 81,891 68,413 55,527 Sand/Gravel/Stone 121,214 115,924 127,614 126,245 99,767 103,801 Contractors 48,773 64,472 81,340 83,266 112,035 102,847 Total 404,315 361,647 348,547 344,836 342,909 321,816

MSHA. Includes workers in mines, processing plants, independent shops and yards, office workers. 21 MINING’S WORKFORCE

According to the Mine Safety and Health Administra- Technological advances, improved engineering tion (MSHA), in 2018, coal, metal, non-metal, stone, methods, advanced training and conscientious sand and gravel segments of the mining industry pro- safety awareness by mine operators and equip- vided approximately 332,000 jobs. ment manufacturers have been principal factors in decreasing fatalities and injuries while simultane- Mining’s average annual pay of more than $79,000 ously improving productivity. The mining indus- is among the highest wage in the U.S. private sec- try’s CORESafety framework is a safety systems tor. Although mining accounts for less than one approach to mine safety and health designed to percent of private sector employment, it has held prevent accidents before they happen. The frame- one of the top average annual pay positions every work integrates leadership and culture into the year since 1980, when the Bureau of Labor Statis- industry management system. Mining has a rate tics began publishing pay levels for industries. of occupational injuries lower than many other sec- Mining operations are the leading employer in tors of the American economy. some parts of the country, particularly rural areas. As such, mining contributes substantially to the ast economic health of those communities. f act Working conditions in mines are demanding, but The mining industry there is no room for unsafe practices or conditions will add more than in today’s mines. While one accident or fatality is 11,000 jobs per year one too many, the rates of all types of accidental over the next 20 years, injuries in the nation’s mines steadily declined in according to the recent decades. Society for Mining, Metallurgy and Exploration (SME)

Coal Mine Productivity, 1980-2018 (Average Tons per Miner per Hour) Year Underground Surface All Mines 1980 1.21 3.27 1.93 1990 2.54 5.94 3.83 2000 4.15 11.01 6.99 2010 2.89 9.47 5.55 2018 3.68 10.36 6.23

Energy Information Administration U.S. Mining Fatalities 1980 - 2018

200 88%

100

1980 1990 1995 2000 2005 2010 2018 22 Mine Safety and Health Administration MINING and the ENVIRONMENT

Restored coal mine land in Wyoming

U.S. mining companies are not only in the business Major laws applicable to coal of producing minerals and coal, but also protect- and mineral mining operations ing the environment. Millions of dollars are spent Federal by mining companies each year to restore mined • Surface Mining Control and lands, protect air and water resources, provide Reclamation Act; habitat for wildlife and create wetlands for migra- • National Environmental Policy Act; tory waterfowl. Minerals also play an important • Clean Water Act; role in providing products that help protect the en- • Safe Drinking Water Act; vironment. • Clean Air Act; • Resource Conservation and Recovery Act; Mining activity is subject to a broad range of state • Superfund and Toxics Release Inventory; and federal laws and regulations, covering every • Endangered Species Act; aspect of exploration, mine development, opera- • National Historic Preservation Act; and tions, protection of wildlife and native vegetation, • Federal Land Policy Management Act. water quality and eventual land restoration. And in State many individual cases, companies go significantly • State environmental policy acts; beyond what is required because they are commit- • State surface water discharge permits; ted to the highest level of environmental steward- • State ground water protection ship. In short, they set their own high standards. laws or regulations; Although activities vary by company, location and • Storm water permits; type of operation, a typical mining approach to • Construction permits for environmental protection generally includes the dams or impoundments; following: • Air quality permits; • Solid waste disposal; 1. Strict compliance with local, state and federal • Water appropriation permits; requirements. • Mine operating permits; 2. Minimizing the impact of actual mining opera- • Reclamation plan approvals or permits; tions on the surrounding environment. • Reclamation bonding; and • Environmental performance bonding. 3. Conducting restoration activities to restore air, land and water resources, and wildlife 23 MINING and the ENVIRONMENT

habitat to pre-mining or better conditions, Governors’ Association and the National Min- with an eye toward long-term sustainability. ing Association, is a voluntary effort focusing on reporting high-priority AML sites and identifying, 4. Fostering constructive dialogue and interac- measuring and reporting on the progress of current tion with individuals and groups who have a cleanup programs on an annual basis. Coal min- positive interest in the company’s environ- ing companies pay taxes into the Abandoned Mine mental stewardship. Land Fund, established by the 1977 Surface Mining 5. Ensuring protection of significant archaeolog- Control and Reclamation Act. That money is used ical and historic resources. to reclaim old surface mines, restore stream beds, treat mine subsidence damage, cover refuse piles Some major areas where environmental efforts are and prevent or control erosion from abandoned focused generally include: mine areas. Overall, U.S. mining is committed to addressing issues raised by abandoned mines by Reclamation of Actively Mined Land — developing strategies to reclaim abandoned sites This means restoring land and environmental val- that have no identifiable owner and will not be ues at an operating or recently operated mining cleaned up under a state or federal regulatory pro- site, whether surface or underground, after the gram. coal or minerals have been extracted. Restoration is as much a part of the modern mining process Water Quality — Operations must, under law, as the actual removal of the resource that will be meet standards for protecting surface and ground processed into raw materials, products or energy. waters from contamination, including acid mine Detailed restoration plans must be approved by drainage. Typically, this involves mitigating any government officials and permitting agencies contaminated drainage, assuring that any dis- before mining begins, and activities are closely charges to surface waters meet legal standards and monitored by federal, state and local officials once protecting wetlands. The five principal technolo- underway. Mining companies must provide finan- gies used to control water flow at mine sites are cial insurance, called “bonding,” to guarantee that diversion systems, containment ponds, ground- restoration will take place at surface mines. With- water pumping systems, subsurface drainage sys- out it, mines will not receive the necessary permits tems and subsurface barriers. The end result of to begin operations. In general, restoration steps these activities can be a radical improvement in include the contouring of affected soil; the place- downstream water quality, including rehabilita- ment of topsoil or an approved substitute on the tion or enhancement of public sport fisheries and graded area; reseeding with native vegetation, increased viability of local species habitats. Care is crops and/or trees; and years of careful monitoring also taken to minimize erosion and excessive runoff to assure success. Ultimately, restored sites are where ground cover has been temporarily removed. returned to many productive uses, including wild- Special flood control and sediment control, such as life habitat, parks, wetlands, recreation areas and the construction of settling ponds, are utilized to commercial development.

Abandoned Mine Lands (AML) — Although modern mining practices and federal and state regulatory programs preclude abandoning mines in an unsafe or unrestored condition, some lands that were mined in bygone eras were abandoned without adequate restoration. Since 1997, the mining industry has operated a major program to address some of the problems of the past. The Abandoned Mine Land Initiative, launched by the Western 24 MINING and the ENVIRONMENT prevent unnecessary damage. Where permitted, dealing with subsidence. With longwall mining, it companies often take the extra step of creating new is easier to anticipate when and where subsidence or enhancing existing wetlands, adding valuable will occur (usually immediately after the mining habitat for waterfowl and other wildlife. operation is completed in a given location). This allows mine operators to carefully monitor changes Air Quality — Mining causes little impact on in the surface and make repairs as needed, working air quality. Steps are taken by mining operations cooperatively with owners of surface structures. to suppress dust from haul roads, rock crushing, Company subsidence programs also include atten- ore concentrating, and the removal, transport and tion to water resources, offering both temporary storage of coal and minerals. Major expenditures and permanent solutions to affected supplies. have been made by mineral smelting and refining operations to control emissions, particularly of sul- Cultural Resources — The National Historic fur dioxide (SO2). SO2 also figures prominently as a Preservation Act and various state laws require concern in the use of coal, where it is a byproduct of assessment and protection of archaeological and combustion by power plants. However, while coal historic resources located on federal and state use by U.S. utilities increased from 320 million tons lands. Mining companies assess, protect and in 1970 to about 700 million tons at present, SO2 mitigate, where necessary, disturbances to these emissions dropped from 15.8 million tons annually resources and often work with state, federal, to 1.2 million tons in 2019. In addition, particulates archaeological, historic, Native American tribal from coal-fired plants declined some 90 percent and other organizations to catalogue, inventory over the same period, according to the U.S. Envi- or display artifacts and other items discovered ronmental Protection Agency (EPA). during the extraction or reclamation process. Some companies erect interpretive signs and centers to Wildlife and Habitat Protection — While wild- make relics available for viewing by the general life protection or mitigation plan is required by law public. for today’s mines, many operations go well beyond the regulations to implement resource protection and habitat improvement programs. Reclamation and water quality procedures are often designed to provide food, shelter and an attractive environment for various native animal species. Many operations institute specific, targeted projects, including sav- ing threatened amphibians; providing Bald Eagle nesting sites; reintroducing once threatened species, such as the peregrine falcon; and improving in-stream fish habitat and populations. For many companies, wildlife habitat restoration, creation or enhancement is seen as the primary beneficial post-mining land use.

Subsidence — Planned surface subsidence is usually gradual, but can sometimes be the abrupt settlement of rock and soil layers above an underground mine. Any surface subsidence must be anticipated and accounted for in the plans for a mining operation. In coal mining, modern procedures, such as longwall mining technology, provide mines with a more effective way of predicting and 25 MINING and the ENVIRONMENT

A closer look at clean coal technologies Because coal is one of America’s most plentiful and readily available energy resources, research has been directed at finding ways to use coal in a more efficient, cost-effective and environmentally friendly manner. The mining industry joined with the U.S. Department of Energy in the Clean Coal Technology Program (CCTP), an industry-government partnership, which has successfully developed and deployed more efficient and cleaner technologies in the marketplace to satisfy America’s need for electricity and a cleaner environment for years to come.

Advanced clean coal technologies can use coal more efficiently, with reduced emissions of sulfur and nitrogen oxides and carbon dioxide (CO2), while also providing distinct advantages over conventional coal systems. Existing coal plants can often be retrofitted with these new technologies, and they can be used for new coal plants to reduce emissions to limits that may be required by new regulations.

Clean coal technologies typically fall into one of four categories: pre-combustion — the washing and sizing stage before coal is burned; combustion — where coal is combined with other substances in the boiler to improve efficiency and remove impurities; post-combustion — where “scrubbing,” chemical cleaning, or use of precipitators remove sulfur, other impurities and particulate matter from emissions going up the flue; and conversion — where heat and pressure convert coal to a gas or liquid that can be further refined and utilized cleanly.

The CCTP has developed advanced pollution controls — such as low nitrogen oxide (NOx) burners now deployed at more than 75 percent of U.S. coal power plants — that help utilities comply with more stringent Clean Air Act requirements. Other NOx control technologies, such as Selective Catalytic Reduction, demonstrate even more impressive air quality improvement capability. As a result of advances pioneered in the program, an additional 70 percent NOx emission reduction from 2000 levels was achieved in 2015 even though coal consumption increased, according to the EPA.

Similarly, the program redefined flue gas desulfurization (FGD) capabilities, bringing to the market more efficient and cost-effective scrubber technology.

Fluidized-bed combustion and integrated gasificationc ombined cycle have entered the marketplace and offer even greater operating efficiency and air quality improvements. According to the Department of Energy, each percentage improvement in operating efficiency translates into a nearly equal percentage reduction in CO2 emissions, a factor important in addressing climate change. In addition, great advances have been made in technologies that enhance the potential to capture, separate and store carbon. Coupled with higher efficiency power plants, carbon capture and storage technologies offer a way to achieve reductions in CO2, while allowing full utilization of plentiful domestic coal resources.

Additionally, new coal combustion systems — using supercritical and ultra-supercritical technologies — operate at higher temperatures and pressures to achieve better efficiencies than conventional systems in addition to significant CO2 reductions. Supercritical steam cycle technology is currently commercially available and in use in several countries. Ultra-supercritical units operating at even higher efficiencies are currently being studied and new steel alloys developed to withstand the increased pressure and to resist corrosion.

26 TRANSPORTATION

Coal and minerals usually get from mine to market in one of three ways — by rail, truck or water transportation. Coal can also be shipped by way of conveyor to “mine mouth” power plants located nearby. In all cases, a modern, reliable and economic transportation infrastructure is an important factor in the overall cost and competitiveness of domestically mined products.

Mined products represent nearly three out of every five tons of revenue freight carried by railroads and approximately one-half of all commodity tonnage handled by barge lines operating on the nation’s inland waterways. Coal shipments alone account for 14 percent of total freight revenue and 31 percent of total freight tonnage transported by Class I railroads. When it comes to barges, 17 percent of coal is moved via our inland waterways. While some mining commodities are shipped intramodally (using a single form of transport between mine and destination), others are moved intermodally (by different types of carriers). For example, a coal shipment might be hauled a shorter distance via truck to a loading terminal, then placed aboard barges or rail hopper cars for the longer trip to a power plant. For many mining products, trucks (and, in the case of coal, also conveyor systems) commonly provide relatively short-haul transportation to railroad tipples and barge terminals. However, rail carriers also originate many shipments and link with barge lines, Great Lakes carriers and dry-bulk oceangoing vessels to complete shipments to domestic and export customers. Railroads Mining products carried by rail typically include coal, crushed stone, sand and gravel, metallic ores, metals and non-metallic minerals. In 2018, these mining commodities accounted for about a third of total rail commodity carloadings in the United States, according to Association of American Railroad (AAR) data. As a single commodity, coal has been a significant annual user of rail transportation. According to AAR, more than 500 million tons of coal were shipped domestically by rail in 2018. Unit trains, large groupings of rail cars assigned to a specific, non-stop route between a mine and power plant, account for more than half of railroad coal shipments. Because the entire train is dedicated exclusively to moving coal in railcars carrying 100 to 125 tons each, economical, high volume shipments are possible. Among other major mining commodities hauled by rail, 2018 totals included: 183 million tons of nonmetallic minerals; 47 million tons of metals and products; 43 million tons of stone, clay and glass products; and 66 million tons of metallic ores. Because mining products represent such an important segment of railroad business, there has been much focus over the past three decades on improving rail efficiency and capacity. In addition to increasing car capacity, many railroads are now using more fuel-efficient alternating current locomotives instead of older direct current models. As with mining, railroads have embraced information technologies, such as electronic data interchange (EDI) to improve efficiency. EDI permits shippers to communicate commodity-specific information to customers, track shipments while in transit and dispatch time-sensitive information, such as bills of lading, invoices and payment for rail car services.

27 TRANSPORTATION

Waterborne Transport Waterborne transportation modes, such as inland waterways, the Great Lakes, coastal shipments and ocean freight, are also vital components in moving coal and minerals to market. Among major U.S. waterborne commodities, coal and coke shipments totaled 224 million tons in 2017, ranking it as the largest, according to U.S. Army Corps of Engineers’ data. Other major mining products, including sand, gravel, iron ore, other ores and metal products, also registered significant tonnage totals. Coal, limestone and iron ore are the major commodities shipped on the Great Lakes. Mining commodities like cement, salt and sand are among other dry bulk cargoes with significant tonnage totals. The largest ships on the Great Lakes can carry more than 70,000 tons of cargo. 2018 Great Lakes Coal and As with rail lines, inland barge lines have increased their effi- Mineral Shipments (net tons) ciency in recent years. Modern 1,500-ton capacity barges are Iron Ore 45,804,433 in service on waterways with shipping channels that allow the use of larger units, including the Ohio and Mississippi rivers and Coal 11,816,332 some of their tributaries, replacing older 1,000-ton capacity Limestone 21,961,950 barges. The 1,500-ton capacity barges carry the equivalent of Lake Carriers’ Association 15 train cars or as many as 60 semi trucks. The average towboat on the Upper Mississippi River pushes 15 of these barges — five barges deep and three abreast. That’s the equivalent of a train three miles long or a line of trucks stretching more than 35 miles. In addition, barge lines make broad use of modern communications and command and control technology for assuring fleets are scheduled in a manner that minimizes the movement of empty barges and opti- mizes the number of loaded barges handled by individual towboats. Truck Transportation Trucks are essential to U.S. mining, whether hauling ore-laden rock from a mine to processing facility or taking a shipment of coal short distances to local power plants or trans-shipment terminals. In coal mining, trucks carry more than 65 million tons annually directly to electric generating facilities and another 10 million tons or more to other consuming sectors. Trucks generally hold 20 to 35 tons of coal per shipment in single unit and combined tractor trailer types of on-road vehicles. The maximum load a truck can carry on highways is regulated by state laws. Special haul trucks that remain on mine property can be of enor- mous size, sometimes holding more than 400 tons of material.

28 TRANSPORTATION

In recent years, advances have also been made in highway trucking operations for movement of mining products. Aluminum truck bodies are being used, allowing higher payloads through reduced empty weights of the trucks, and more powerful truck engines expedite truck shipments. Newer technologies in transporting ore from the mine to the processing location by truck include trolly-assist systems for steep grade transport, GPS monitoring systems for movement control and remote- control truck operation. The average car contains: • 2,000 lbs. iron & steel Other Shipping Methods • 300 lbs. aluminum • 50 lbs. carbon Conveyors and pipelines are two additional transportation methods • 40 lbs. copper, employed in mining. Versatile conveyor systems and aerial tramways (75 lbs. for a hybrid) are normally used to move coal or mineral ore from production sites • 40 lbs. silicon to storage and transportation facilities, processing plants or nearby • 24 lbs. lead power plants. Tramways usually cover relatively short distances, while • 22 lbs. zinc conveyors can be several miles long. • 17 lbs. manganese • 15 lbs. chromium • 9 lbs. nickel • 4.5 lbs. magnesium • 2 lbs. sulfur • 1 lb. molybdenum • and smaller amounts of vanadium, platinum, What are the lightest and the antimony, barium, heaviest metal minerals? beryllium, cobalt, gallium, gold, neodymium, indium, palladium, rhodium, silver, Lithium is the lightest metal and third strontium, tin, titanium, lightest of all elements. Platiniridium, a tungsten and zirconium natural alloy of two members of the plati- USGS, NMA, SME num group, is the heaviest.

The space shuttle’s super lightweight external fuel tank was made from an alloy of lithium and aluminum. It provided the liquid ast hydrogen fuel required for liftoff. The use of act the lithium alloy provided a 7,000 lb. weight f reduction over previous tanks, and each The Institute for Defense pound in weight reduction increased the Analysis estimates that shuttle’s cargo capacity by nearly a pound. roughly 750,000 tons Photo: NASA of minerals are required annually to maintain our national defense.

29 EXPORTS and TRADE

Exporting U.S. mining products has a significant positive impact on the nation’s balance of trade. In 2018, U.S. exports of raw and processed mineral materials totaled an estimated $95 billion, according to the USGS. American coal exports for 2018 were 115 million tons, valued at about $12 billion. In addition, the United States is a significant exporter of mining machinery and equipment and has pioneered the development and commercialization of clean coal technologies, for which a growing overseas market is possible in the near future. ast Among major minerals, the U.S. is a leading world producer of beryllium, diatomite, f act gold, helium, soda ash (trona) and coal. The most significant exported U.S. mineral The U.S. is rich in commodities include iron ore, soda ash, copper, gold, zinc, titanium and cement. many of the miner- Despite the United States’ abundant mineral supply, in recent years, the U.S. has als it requires and is increasingly relied on imports to meet its needs for some minerals, particularly a major exporter of strategic and critical minerals. The U.S. share of worldwide investment in miner- some commodities, als mining has declined over the last 20 years due to a time consuming and highly including iron ore, inefficient permitting system. According to USGS data, strategic mineral com- soda ash, copper modities, for which the U.S. imported more than half of its supply in 2018, included titanium, silver, zinc, rare earths, platinum and others (see table, page 32). Many and cement. of these strategic and critical minerals are crucial for manufacturing jet aircraft, satellites, communications equipment and other items vital for national security. In recent years, America’s import reliance on processed mineral materials has risen to more than $152 billion annually, according to USGS. U.S. coal is exported to more than 70 nations. Major markets for American coal include India, the Netherlands, Japan, South Korea, Brazil and Canada. The U.S. exports both steam coal for generating electricity and metallurgical coal used in the steel-making process. Metallurgical coal comprised about 53 percent of U.S. coal exports in 2018, with steam coal making up the remainder. The United States tends to be a “swing” supplier in overseas steam coal markets, increasing shipments when other lower-cost competing exporting nations (primarily Colombia, Indonesia, Australia, Russia and South Africa) cannot meet demand.

Exports of Selected Mineral Commodities and Coal, 2014-2018 (Metric Tons) Commodity 2014 2015 2016 2017 2018e Coal* 97,257,000 73,958,000 60,271,000 96,953,000 115,632,000 Iron Ore 12,100,000 8,030,000 8,770,000 10,600,000 13,000,000 Soda Ash (Trona) 6,670,000 6,400,000 6,760,000 6,990,000 6,900,000 Copper 410,000 392,000 331,000 237,000 230,000 Zinc 644,000 708,000 597,000 682,000 870,000 Cement 1,404,000 1,288,000 1,283,000 1,035,000 1,000,000 Lead 357,000 350,000 341,000 269,000 370,000 Lime 320,000 346,000 329,000 391,000 350,000 Figures are rounded. * short tons e = estimated. Source: U.S. Geological Survey, Mineral Commodity Summaries 2019; Energy Information Administration. 30 EXPORTS and TRADE

As the globalization of mining has increased, the opening or expanding of mines in overseas locations has created more opportunities for marketing U.S. mining equipment in foreign countries. According to 2018 analysis by Freedonia Group, growth in industrializing countries like China and India is creating a global mining machinery market valued at more than $98 billion. Mining Equipment Exports According to U.S. government data, more than $2 billion worth of U.S. mining and minerals processing equipment was shipped to overseas destinations in 2018. In addition, another $6.2 billion of construction machinery, including surface mining equipment, was shipped to foreign destinations in 2018. The table below shows in more detail the types of products mining machinery equipment suppliers shipped in 2016 (data latest available).

Shipments of Mining and Construction Machinery Product Value (million $) Mining and Mineral Processing Equipment — 2016 $3,185.7 Underground mining machinery (except parts) $1,147.8 Mineral Processing and benefication machinery (except parts sold seperately) $151.7 Crushing, pulverizing and screening (except parts sold seperately) $450.1 Drills and other mining machinery (except parts sold seperately) $198.8 Parts and attachments for mining machinery and equipment (sold seperately) $1,035.6 Mining machinery and equipment, not specified by kind, total $201.7 Construction Machinery — 2016 $24,010.4 Power cranes, excavation loaders, dozers, tractors, trucks, trailers, mixers, etc. $17,383.5 Other construction machinery and equipment (excluding parts) $3,526.0 Parts for construction machinery and equipment (sold seperately) $2,428.6 Construction machinery, not specified by kind, total $672.3

Department of Commerce, Bureau of the Census. Data latest available.

31 EXPORTS and TRADE Selected U.S. Mineral Materials Ranked by Net Import Reliance, 2018 Commodity Percent Major Sources Arsenic (Trioxide) 100 Morocco, China, Belgium Asbestos 100 Brazil, Russia Cesium 100 Canada Fluorspar 100 Mexico, Vietnam, South Africa, China Gallium 100 China, United Kingdom, Germany, Ukraine Graphite (Natural) 100 China, Mexico, Canada, Brazil Indium 100 China, Canada, S. Korea, Taiwan Manganese 100 South Africa, Gabon, Australia, Georgia Mica (Sheet, Natural) 100 China, Brazil, Belgium, Austria Nepheline Syenite 100 Canada Niobium (Columbium) 100 Brazil, Canada, Russia, Germany Rare Earths (Compounds, Metals) 100 China, Estonia, France, Japan, Rubidium 100 Canada Scandium 100 Europe, China, Japan, Russia Strontium 100 Mexico, Germany, China Tantalum 100 Brazil, Rwanda, Australia, Congo Thorium 100 India, United Kingdom Vanadium 100 Austria, Canada, S. Korea, Russia Gemstones 99 India, Israel, Belgium, South Africa Bismuth 96 China, Belgium, Mexico, S. Korea Yttrium 95 China, Estonia, Japan, S. Korea Potash 92 Canada, Russia, Belarus, Israel Titanium Mineral Concentrates 91 South Africa, Australia, Canada, Mozambique Diamond (Dust, Grit, Powder) 89 China, Ireland, S. Korea, Romania Antimony (Oxide) 85 China, Thailand, Belgium, Bolivia Zinc 85 Canada, Mexico, Peru, Australia Barite 84 China, India, Mexico, Morocco Rhenium 84 Chile, Germany, Belgium, Poland Stone (Dimension) 82 Brazil, China, Italy, Turkey Tin 78 Indonesia, Malaysia, Peru, Bolivia Abrasives (Fused, Al. Oxide, Crude) 765 China, France, Hong Kong, Canada Abrasives (Silicon Carbide, Crude) 75 China, Netherlands, South Africa, Romania Bauxite 75 Jamaica, Brazil, Guinea, Guyana Tellurium 75 Canada, China, Germany Titanium (Sponge) 75 Japan, Kazakhstan, Ukraine, China Platinum 73 South Africa, Germany, United Kingdom, Italy Chromium 71 South Africa, Kazakhstan, Russia Peat 70 Canada Garnet (Industrial) 68 Australia, India, South Africa, China Silver 65 Mexico, Canada, Peru, S. Korea Cobalt 61 Norway, China, Japan, Finland Nickel 52 Canada, Norway, Australia, Russia Germanium 50 China, Belgium, Germany, Russia Iodine 50 Chile, Japan Iron Oxide Pigments (Natural) 50 Cyprus, Spain, France, Austria Iron Oxide Pigments (Synthetic) 50 China, Germany, Brazil, Canada Lithium 50 Argentina, Chile, China, Russia Tungsten 50 China, Bolivia, Germany, Canada Aluminum 50 Canada, Russia, United Arab Emirates, China USGS Minerals Commodity Summaries 2019 32 GLOSSARY

aggregate: Uncrushed or crushed gravel, crushed ensure that the regulatory authority will have suf- stone or rock, sand or artificially produced inorgan- ficient funds to reclaim the site in the event the ic materials that form the major part of concrete. company fails to complete the reclamation plan approved in the permit. alloy: A substance with metallic qualities that is composed of two or more chemical elements, of Btu: British thermal unit. This is a measure of the which at least one is an elemental metal. energy required to raise the temperature of one pound of water one degree Fahrenheit. On aver- anthracite: See “ranks of coal.” age, coal contains about 22 million Btu per ton.

assayer: One who analyzes ores and alloys, espe- bullion: Mixture of gold and silver in cast bars. cially bullion, to determine the value and proper- Also called dore. ties of precious metals. cage: An elevator used to carry people and ma- auger mining: A form of underground coal mining terials up and down a mine shaft. Cages may be that uses an auger, which looks like a large car- single or multidecked. Often there are two cages penter’s wood drill. The auger bores into a coal in simultaneous operation in separate areas of the seam and discharges coal out of the spiral onto shaft, traveling in opposite directions. a waiting conveyor belt. When mining is finished, the openings are backfilled. This method is usu- captive mine: A mine whose coal is used largely or ally employed to recover any additional coal left totally by its owners or a subsidiary operation. in deep overburden areas that cannot be reached economically by contour or area mining. clean coal technologies: A number of innovative technologies designed to use coal in a more effi- backfill: Refilling an area where overburden has cient and cost-effective manner while enhancing been removed. May also refer to the material used environmental protection. These include process- to refill an excavation. es applied before, during and after combustion, and also involve those that change coal into a gas base metals: Any of the non-precious metals — or liquid. copper, lead and zinc — are usually considered the primary base metals, but tin, aluminum and mag- coal resources: Total coal deposits, both identified nesium are also among those important to modern and undiscovered. The World Energy Conference society. estimated there may be as much as 14 trillion short tons of coal worldwide; the United States is estimated to have 4 trillion tons of coal resources by bedrock: Any solid rock exposed at the surface of the earth or overlain by unconsolidated material. the USGS. A bed or stratum of coal. Usually ap- bioleaching: Addition of naturally occurring bacte- coal seam: ria to extract or remove a soluble substance from plies to a large deposit. ore. coke: A hard, dry carbon substance produced by heating coal to a very high temperature in the ab- bituminous coal: See “ranks of coal.” sence of air. Coke is used in the manufacture of iron and steel. blasting: The operation of breaking coal, ore or rock by boring a hole in it, inserting an explosive charge, and detonating or firing it. Also called shot concentrate: The result of separating ore or metal firing. from its containing rock or earth. Underground mining in which bond: As a prerequisite for obtaining a mining per- continuous mining: mit, companies must post a reclamation bond to the continuous mining machine cuts coal from the face (see “face”) and loads it onto conveyors or

33 GLOSSARY into shuttle cars in a continuous operation. Often exploration: The search for coal, mineral or ore by these machines are highly automated and can be geological surveys, prospecting, GPS or satellite operated by remote control. Accounts for about location, or use of tunnels, drifts or boreholes. 45 percent of U.S. underground coal production. face: The exposed area of a coalbed from which conventional mining: A deep mining method that coal is extracted. includes inserting explosives in a coal seam, blasting the seam and removing the coal onto a convey- flotation: Separating minerals from other materials or or shuttle car. Accounts for less than 5 percent by floating away materials of lower specific grav- of total underground coal production. ity, while heavier materials sink. core: The sample of rock obtained through the use fluidized-bed combustion: A clean coal technolo- of a hollow drilling bit, which cuts and retains a sec- gy process to remove sulfur from coal combustion, tion of the rock penetrated, usually to determine as well as limit the formation of nitrogen oxides. the interior composition or the hidden condition. The process involves suspending crushed coal and limestone in the bottom of a boiler by an upward deep mine: An underground mine. stream of hot air. While the coal is burned in this liquid-like mixture, sulfur from combustion gases demonstrated reserves: Coal deposits that are combines with the limestone to form a solid com- potentially minable on an economic basis with ex- pound recovered with the ash. isting technology. The U.S. has an estimated 481 billion tons of demonstrated reserves. fly ash: The finely divided particles of ash entrained in gases resulting from the combustion of fuel. At deposit: A natural occurrence or accumulation of coal-fired power plants, fly ash is captured by spe- mineral material, coal, iron ore, oil or gas. cial equipment, usually either electrostatic precipitators or baghouses. Fly ash and other forms dragline: A large excavating machine used in the of coal ash are useful by-products — about 25 mil- surface mining process to remove overburden (see lion tons are used each year in major concrete en- “overburden”). The dragline has a large bucket sus- gineering projects, such as highway construction. pended from the end of a huge boom, which may be 275 feet long or larger. The bucket is suspended by formation: Any rock unit conspicuously different cables and capable of scooping up huge amounts of from adjacent rock units. overburden as it is dragged across the excavation area. The dragline, which can “walk” on huge pon- fossil fuel: Fuel such as coal, crude oil or natural toon-like “feet,” is one of the largest land-based ma- gas, formed from the fossil remains of organic machines in the world. terial. drift mine: A coal mine entered directly through a Frasch sulfur deposit: Native sulfur mined by the horizontal opening drilled into the side of a hill or Frasch hot water process, in which superheated mountain. This mining method is used in hilly or water is forced into the sulfur deposit for the pur- mountainous areas. pose of melting the sulfur. The molten sulfur is then pumped to the surface. electrostatic precipitator: An electrical device used in removing particles (see “fly ash”) from gasification: Any of various processes by which combustion gases prior to release from a power coal is turned into low, medium or high-Btu gas. plant’s stack. General Mining Law: The primary statute that gov- excavator: A large number of power-operated dig- erns the right to mine locatable minerals on unap- ging and loading machines, used increasingly in propriated public domain lands. Though enacted in open-pit mining and quarrying. 1872, it has been amended many times.

34 GLOSSARY grade: 1. The classification of an ore according to Can also refer to a tabular deposit of a valuable the desired material in it or according to value. 2. mineral confined within definite boundaries. In surveying, the gradient of a traveling way, sluice, slope, etc. longwall miner: A deep mining machine that uses a steel plow or rotating drum that is pulled me- hardrock minerals: Locatable minerals that are nei- chanically back-and-forth across a long face of ther leasable minerals (coal, oil, phosphate, etc.) coal. The loosened coal falls onto a conveyor for nor saleable mineral materials (sand and gravel, removal from the mine. Longwall mining is highly etc.). Hardrock minerals include copper, lead, zinc, productive and accounts for about 50 percent of magnesium, nickel, tungsten, gold, silver, benton- total U.S. underground coal production. ite, barite, feldspar, fluorspar and uranium. man car: A vehicle used to transport miners to the haulageway: The main transportation tunnel for working sections of a deep mine. deep mines in which rail tracks have been laid for mine cars. metallic minerals: Minerals with a high specific gravity and metallic luster, such as gold, silver, highwall: Unexcavated face of exposed overbur- copper, titanium, rutile, tungsten, uranium, tin, den and coal in a surface mine or in a face or bank lead, iron, etc. In general, the metallic minerals are on the uphill side of a contour mine excavation. good conductors of heat and electricity. hopper cars: Open freight cars with a floor sloping metallurgical coal: Various grades of coal suitable to one or more hinged doors for discharging bulk for carbonization to make coke for steel manufac- materials. ture. in situ gasification:The gasification of underground methane: A gas formed naturally from the decay coal deposits through partial combustion. of vegetative matter, similar to that which formed coal. The principal component of natural gas, jumbo drill rig: A drill carriage on which several methane is frequently encountered in underground drills of drifter type are mounted. Drills are cut- coal mining operations and is kept within safe lim- ting tools designed to form a circular hole in rock, its through the use of extensive mine ventilation metal, wood or other material. In mining, drills are systems. In recent years, coalbed methane has used for exploration core drilling, holes for explo- been recognized as an important energy resource, sives, etc. and its production for this purpose has increased. leaching: The action of percolating liquid through mine mouth power plant: A steam-electric power ore to remove the soluble parts. plant built close to a coal mine. Because of this proximity, the coal is often delivered to the plant lignite: See “ranks of coal.” by tramway or covered conveyor. liquefaction: The process of converting coal into a minerals: Scientifically, a naturally formed inor- synthetic liquid fuel, similar in nature to crude oil ganic solid (element or chemical compound) with and/or refined products, such as gasoline. a limited range in chemical composition and with an orderly internal atomic arrangement that de- locatable minerals: Those minerals – primarily me- termines crystalline structure and physical prop- tallics – that can be claimed and mined on public erties. Legally, an organic or inorganic substance lands under the General Mining Law; these do not occurring naturally, with characteristics and eco- include minerals such as coal, oil, phosphate so- nomic uses that bring it within the purview of min- dium, sulfur, or sand and gravel. eral laws; a substance that may be obtained under the applicable laws from public lands by purchase, lode deposit: An ore deposit, usually referring to lease or claim. a vein or veins of ore that can be mined as a unit. 35 GLOSSARY mining claim: That portion of the public mineral outcrop: Coal that appears at or near the surface. lands that a person may claim for mining purposes in accordance with the General Mining Law, as overburden: Layers of earth and rock covering a amended. There are four types of mining claims: coal seam or mineral deposit. lode, placer, millsites and tunnel sites. patent: A government deed; a document that con- Mohs’ hardness scale: Quantitative units by which veys legal title to public lands to the patentee. the scratch hardness of a mineral is determined. The units of hardness are expressed in numbers placer deposit: An alluvial marine or glacial depos- ranging from 1 (talc) to 10 (diamond). it resulting from the crumbling and erosion of solid rocks, and often containing valuable minerals. mountaintop mining: A method of surface mining practiced in the Appalachian coal fields of the portal: Any entrance to a mine. eastern United States. Mountaintop mining allows the mine operator to remove layers of dirt and rock preparation plant: A facility, usually located on a covering a coal seam, making the entire deposit mine site, that crushes, sizes and washes coal prior economical and safer for extraction. Valley fills — to shipment. a critical component of mountaintop mining -- are carefully constructed to ensure the safe deposit of ranks of coal: The classification of coal by degree rock and dirt from the surface mine into adjacent of hardness, moisture and heat content. The major valleys. Valley fills are not unique to mining. Hun- ranks, from lowest to highest quality, are lignite, dreds of valley fills were constructed throughout subbituminous, bituminous and anthracite. For the country during the building of the Interstate more information, see the “Resources” chapter. Highway System. reclamation: The restoration of land and environ- multiple use: The standard for federally managed mental values to a mining site. Reclamation opera- land. A combination of balanced and diverse re- tions are sometimes started where the coal or min- source uses that takes into account the long-term eral has already been taken from a mine, even as needs of future generations for renewable and production operations are taking place elsewhere non-renewable resources, including recreation, at the site. This process commonly includes re- range, timber, minerals, watershed, and wildlife, contouring or reshaping the land to its approxi- along with natural scenic, scientific and historical mate original appearance, restoring topsoil and values. planting native grasses, trees and ground covers. Mining reclamation is closely regulated by both non-metallic minerals: Minerals (carbon, dia- state and federal law. mond, coals, bitumen, asphalt, boron, sulfur, rock salt, etc.) that lack the properties of the metallic recoverable reserves: The amount of coal that minerals. can be recovered from the Demonstrated Reserve Base. The recovery factor for underground coal non-renewable resources: Resources that are not mines is about 60 percent and for surface mines replaced or regenerated naturally within a reason- about 80-90 percent. able period of time, such as fossil fuels or minerals. reserves: Known identified resources from which a open pit: A mine or excavation open to the sur- usable mineral commodity can be technologically, face. Refers primarily to mines of metal ores; dis- economically and legally extracted at the time of tinguished from coal surface mines. determination. ore: Rock that contains important minerals, includ- resources: A broad term for discovered or still ing metals. undiscovered concentrations of minerals in such form that a usable commodity can be extracted now or in the future.

36 GLOSSARY

roof bolting: A method of supporting the ceilings stope: An excavation from which ore has been of underground mines by inserting long steel bolts removed in a series of steps. into holes bored into the strata forming the roof. strategic minerals: Those minerals considered rotary drill: A drill machine that rotates a rigid, tu- essential for a country’s economic and defense bular string of rods to which is attached a bit for needs, such as metals for defense weapons, cutting rock to produce boreholes. satellite communications, automobile parts and medical instruments. scrubber: Any of several forms of chemical/physical devices that remove sulfur compounds formed subbituminous coal: See “ranks of coal.” during coal combustion. Technically known as flue gas desulfurization systems, they combine the sul- surface mine: A mine in which the coal lies near fur in gaseous emissions with another chemical the surface and can be extracted by removing the medium to form an inert sludge. covering layer of overburden. About 66 percent of total U.S. coal production comes from surface shaft: A narrow, deep excavation used for finding mines. or mining ore or coal. The term is often applied to vertical shafts, as distinguished from a decline or tailings: The waste material left after hardrock inclined shaft. mining and milling processes have been completed. shortwall: A deep mining method in which small areas are worked by a continuous miner in con- tipple: A surface processing structure for cleaning junction with longwall-like hydraulic roof supports. and sizing coal and automatically loading it onto Accounts for less than one percent of total under- rail cars or trucks for movement to market. ground coal production. tunnel: A horizontal underground passage that shuttle car: A self-discharging truck, usually with opens to the surface at both ends. rubber tires or caterpillar-type treads, used for receiving coal or ore from the loading or mining turbine: A machine in which rotating vanes are machine and transferring it to an underground driven by a steam generator to produce electricity. crusher loading point, mine railway or belt conveyor system. underground mine: Also known as a deep mine. Usually located several hundred feet below the slurry pipeline: A pipeline similar to that used by earth’s surface, an underground mine’s coal is re- the petroleum and natural gas industries, designed moved mechanically and transferred by shuttle for transporting pulverized coal in a liquid medium. car or conveyor to the surface. Most underground Water is usually used, although research is mines are located east of the Mississippi River and focusing on other compounds, such as oil, liquid account for about 34 percent of total annual U.S. methane and carbon dioxide. coal production. slope mine: A mine with an opening that slopes unit train: A long train of between 60 and 150 or upward or downward to the seam. It must also more hopper cars, carrying only coal between a have adjoining vertical shafts for air ventilation and single mine and destination. A typical unit train emergency use. can carry at least 10,000 tons of coal in a single shipment. smelter: A furnace in which the raw materials are melted, and metals are separated from impurities. steam coal: Coal used by electric power plants and industrial steam boilers to produce electricity. 37 National Mining Association | 101 Constitution Ave., NW | Suite 500 East | Washington, DC 20001 | www.nma.org